Launches client with the following parameter. Returns 1 if successful. Returns 0 otherwise.

index : index results/errors by server if set to 'forward'
timeout : global timeout in seconds
max_buf : max number of bytes in each read buffer
multiplex : max number of threads
verbose : report progress to a file handle opened for write.

Returns undef if no error. Returns a string if a global error occurred, else if errors occurred with individual client/server connections, returns a HASH reference indexed either by server or by result. (see the index parameter of run().)